It has been only a short while since humanity has come to realize that earth was neither an infinite nor inorganic space. Its resources are limited; earth is sensitive and alive. If the population of mankind continues to grow, then we will soon lose the space for housing and living. And this problem is following our shadows even up to our deathbeds, as securing a patch of land in cemetery is becoming more and more difficult in some countries. Land, which has assumed the central role in our lives for a long time, is running short.

Now I would like to analyze human history in a somewhat different light, namely, so-called physical history.

Matter on this earth consists of three phases: solid, liquid, and gas. And if we ever have to make a metaphor, I think we would agree that our life would fall onto the category of “solid” as we have cultivated and lived on land, which has born great importance to mankind. In fact, until recently, humanity has waged numerous wars to acquire more land, which was considered as an asset of a country and often, a sign of wealth. The world map that we have today is the result of such infinitely many wars occurred among tribes, ethnicities, and states.